JEE Main 2026 · 5 Apr · Shift 2 · Chemistry Q75

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ChemistryInteger+4 / -1Question 75 of 75

For a reaction $\ce{A -> P}$ at T K, the half life ( $t_{1/2}$ ) is plotted as a function of initial concentration $[\mathrm A]_o$ of A as given below.

The value of $x$ in the given figure is ________ s (Nearest integer)

t½ (s) against [A]₀ (mol L⁻¹): a straight line through the origin; at [A]₀ = 1.5 × 10⁻³ it reads x, and at 4 × 10⁻³ it reads 240.

Your answer

Answer and worked solution

Official answer: 90

Order. $t_{1/2}$ is proportional to $[\mathrm A]_o$ (a straight line through the origin). That is zero order: $t_{1/2}=\dfrac{[\mathrm A]_o}{2k}$ .

Read off x.
$x=240\times\frac{1.5\times10^{-3}}{4\times10^{-3}}=90\text{ s}.$

Answer: 90

Topics:Half-life Order and molecularity

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JEE Main 2026 · 5 Apr · Shift 2, Chemistry question 75